Embarking on the restoration of Lloyd Street Synagogue in Baltimore — built in 1845, the oldest synagogue in Maryland and the third-oldest in the nation — Jewish Museum of Maryland trustees, the architect, and the general contractor knew every choice they made would be under intense scrutiny from the Maryland Historical Trust.

“From the footing to the roof's ridgeline, nothing was exempt from the agency's review and approval,” Jewish Museum of Maryland trustee Lee Rosenberg said.

Among the renovations that could have impacted the aesthetics of the two-story Greek Revival-style structure negatively was the installation of an air-conditioning system.

Initially, the design/build team looked into conventional comfort systems.

“This would have involved creative placement of ductwork and probably having to alter the space to accommodate it,” John Lederer, principal owner of Frosty Refrigeration Company Inc., the general contractor, said.

After careful consideration of all of its options, the team chose an intelligent, energy-efficient VRV III heat-pump system from Daikin AC to deliver both cooling and heating with advanced zoning capabilities.

Lederer and preservation architect John R. Srygley, AIA, of JRS Architects Inc. worked closely with Daikin on the final system design.

The system consists of twinned 10-ton outdoor VRV III condensing units supplying 20 tons of capacity to the upper level of the space, another unit supplying 8 tons of capacity to the lower level, and 21 1- and 2-ton floor console models lining the interior walls of both floors serving as supply- and return-air units. The configuration of inside and outside units was the optimum solution for the space limitations of the building, Lederer said.

“The Daikin FXLQ floor console models fit neatly under the low historic synagogue windows,” Lederer said. “They enabled us to maintain the aesthetics of the structure with minimal disruption. These console units rest flush against the wall and are actually less obtrusive than the radiators that had previously been there.”

The three outdoor condensing units are located in a narrow alley behind the building.

“Several of the HVAC alternatives we were looking at would have required placing the outdoor equipment on our roof, which really would have been contrary to what the historic preservationists would have been willing to accept,” Lederer said.

Since being commissioned during the fall of 2009, the system has performed “above our expectations,” Lederer said.

“The heat production, even in freezing weather, as well as the acoustical performance, have been just tremendous,” Lederer said. “The balance of air conditioning in the summer in every corner of the synagogue has been remarkable as well.”

Lederer said each Daikin console has a built-in return-air sensor that helps to vary the flow of refrigerant to provide increased comfort where and when it is needed.

“It acts independently in its own little zone,” Lederer said.

For example, when the sun streams in south-facing windows, the units run at a higher capacity than those on the opposite side, where the space is cooler. Additionally, multiple consoles on each floor are controlled by a centralized seven-day programmable controller.

Another feature helped to ensure the system's selection.

“Because of the location of our synagogue, which is very close to Baltimore's Inner Harbor and very close to sea level, we had to contend with moisture concerns,” Rosenberg said. “After doing a thorough study, we knew that the Daikin system-control logic would help manage the discomfort due to high humidity levels better than standard on/off systems. We are very sure we are meeting the very stringent requirements for moisture, humidity, and temperature that are always a concern in a museum setting.”

Also important is that the new equipment is virtually unnoticeable to synagogue visitors.

“There is no evidence that any changes have been made,” Rosenberg said. “Even someone who has been there 50 times would not notice the change. But in the warmer weather especially, they certainly will feel a lot more comfortable than they did in the past.”